The present invention relates broadly to a subsurface inspection probe and, in particular, to a subsurface pipeline inspection system for inspecting pipe bedding surrounding subsurface pipelines.
Traditionally, subsurface pipelines such as sewerlines and storm water drains have been inspected using manual access. This involves a person entering the pipeline system and carrying out a manual inspection of pipe walls. However, this method reveals only surface defects in the pipe walls and gives no information on defects in the surrounding soils. This method also has inherent dangers and health risks for the person carrying out the inspection.
Remote Controlled Closed Circuit Television (CCTV) has also been employed in inspecting subsurface pipelines. This method involves the use of a small camera which is mounted on the end of along flexible cable. The camera is placed into the pipeline through an access opening and is then remotely controlled from the surface. This method removes the dangers involved in a person entering the pipeline, however, this method again reveals only surface defects in the pipe walls and gives no information on defects in the surrounding soils.
In order to inspect the bedding of a subsurface pipeline and to detect defects in the surrounding soils, more elaborate techniques have been employed such as ground probing radar (GPR) and seismic methods. The GPR systems consist of a transmitting antenna emitting electromagnetic radiation (le: generated by an oscillator), a receiving antenna and an energy detecting device, or receiver. A portion of the transmitted signal is intercepted by a reflecting object, such as the wall of the pipeline, and is reradiated in all directions. The energy reradiated in the back direction is collected by the receiving antenna and delivered to a receiver, where it is processed to detect the presence of the pipeline. The time taken for the radar signal to travel through the pipeline and back is measured. Defects in the soil surrounding the pipeline, which can result in deformation or collapse of the pipeline, are detected by using the time measurement and known soil characteristics, and comparing this information to site drawings.
Seismic methods, including techniques such as tomography, measure the velocity and refraction of seismic waves in a manner similar to the electromagnetic radiation measurements of GPR. However, seismic methods are based on long wavelengths with a resulting reduction in resolution. Further, both the GPR and seismic methods require complex equipment and processing which results in low productivity and unacceptably high costs.
It is an object of the present invention to substantially overcome, or at least ameliorate, one or more of the deficiencies of the above mentioned arrangements.
According to one aspect of the present invention there is provided, a time domain electromagnetic (TEM) subsurface analysis system characterized by at least part of said system being configured for insertion along a sub-surface conduit for emission and reception of TEM signals.
According to another aspect of the present invention there is provided a time domain electromagnetic (TEM) subsurface analysis system characterized by a mobile TEM signal transmitter and receiver module operatively coupled to a stationary controller and TEM recorder module and by said mobile module being self-powered and processing said electromagnetic response prior to communicating the processed response to said stationary controller.
According to still another aspect of the present invention there is provided a time domain electromagnetic (TEM) subsurface analysis system incorporating at least one transmitter coil and a plurality of receiver coils characterized in that said coils are configured as part of a mobile module including a multiplexer arrangement for coupling at least said receiver coils in a predetermined manner to a recorder module.
According to still another aspect of the present invention there is provided an inspection system comprising a transmitter and a receiver configured for communication with a remotely positioned processing means, said transmitter and receiver being arranged as a mobile apparatus configured for insertion into a duct, and said transmitter being configured to transmit an electromagnetic signal to induce an electromagnetic response in said duct, said electromagnetic response being detected by said receiver, characterized in that, said mobile apparatus is self-powered and processes said electromagnetic response prior to communicating the processed response to said remotely positioned processing means as a discrete signal.
According to still another aspect of the present invention there is provided an inspection system, said system comprising:
a first apparatus configured for insertion into a duct and comprising:
(i) transmission means for transmitting an electromagnetic signal to induce an electromagnetic response in said duct and material surrounding said duct;
(ii) detection means for detecting said electromagnetic response;
(iii) conversion means for converting said electromagnetic response to a discrete signal; and
(iv) communication means for reading and communicating said discrete signal to a second apparatus positioned remotely to said first apparatus;
said second apparatus comprising:
(i) storage means for storing said discrete signal;
(ii) processor for processing said discrete signal; and
(iii) display for displaying said processed discrete signal.
According to still another aspect of the present invention there is provided a method of inspecting a subsurface pipeline utilizing an inspection system, said system comprising:
a first apparatus configured for insertion into a duct and comprising:
(i) transmission means for transmitting an electromagnetic signal to induce an electromagnetic response in said duct and material surrounding said duct;
(ii) detection means for detecting said electromagnetic response;
(iii) conversion means for converting said electromagnetic response to a discrete signal; and
(iv) communication means for reading and communicating said discrete signal to a second apparatus positioned remotely to said first apparatus;
said second apparatus comprising:
(i) storage means for storing said discrete signal;
(ii) processor for processing said discrete signal; and
(iii) display for displaying said processed discrete signal, said method comprising the steps of transmitting a first electromagnetic signal from said transmission means;
detecting a second electromagnetic signal at said detection means;
amplifying said second electromagnetic signal;
sampling said amplified signal;
converting said sampled signal to a digital signal utilizing said conversion means;
communicating said digital signal from said first apparatus to said second apparatus;
storing said digital signal in said storage means; and
displaying said digital signal on said display.